The current ultra-thin-body-BOX (UTBB) substrate on insulator technology allows for multi-Vt scheme by applying bias on the back plate. This technique can be implemented by using a single shallow trench isolation (STI) depth scheme or a double STI depth scheme. The current techniques, however, involve complicated scheme of back plates and various bias, with each back plate requiring a contact on the bulk substrate region. Such requirements severely limit the design flexibility and scaling for advanced technology.
Therefore, it may be desirable to develop transistor structures that allow for reduced bulk substrate contacts and for dynamic biasing of back-plates or p-wells.